Add Emacs config with install scripts for laptop and work

Shared: init.el / early-init.el with Vertico stack, Corfu, Eglot,
treesit-auto, Catppuccin Mocha, doom-modeline, Magit, avy, harpoon,
embark, wgrep, expand-region, envrc, org-mode, and drop-in lang loader.

Lang configs split by stow target:
- shared: elisp, org
- laptop: C/C++, Rust, Go, LaTeX (AUCTeX + latexmk + Zathura)
- work:   C#, JS/TS/HTML/CSS/React (apheleia+prettier), Copilot

install-personal.sh: Fedora — gcc/clang, rustup, Go, texlive, zathura
install-work.sh: Ubuntu 24.04 WSL — dotnet-sdk-10.0, Node 22 via nvm, ts-ls

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

shared/.config/emacs/early-init.el

@@ -0,0 +1,7 @@
+;;; early-init.el  -*- lexical-binding: t -*-
+
+;; Defer GC during startup; restore to a reasonable limit after
+(setq gc-cons-threshold (* 128 1024 1024))
+
+(add-hook 'emacs-startup-hook
+          (lambda () (setq gc-cons-threshold (* 16 1024 1024))))